IABSD.fr/src/lib/libutil/imsg.c

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• Author : kettenis
  Date : 2017-12-14 09:27:44
  Hash : 8c897735
  Message : Make a few internal symbols static and add a Symbols.map version script to control which symbols are exported from the shared library. ok guenther@, deraadt@, jca@

• lib/libutil/imsg.c

• /*	$OpenBSD: imsg.c,v 1.16 2017/12/14 09:27:44 kettenis Exp $	*/
  
  /*
   * Copyright (c) 2003, 2004 Henning Brauer <henning@openbsd.org>
   *
   * Permission to use, copy, modify, and distribute this software for any
   * purpose with or without fee is hereby granted, provided that the above
   * copyright notice and this permission notice appear in all copies.
   *
   * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
   * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
   * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
   * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
   * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
   * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
   * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
   */
  
  #include <sys/types.h>
  #include <sys/queue.h>
  #include <sys/socket.h>
  #include <sys/uio.h>
  
  #include <errno.h>
  #include <stdlib.h>
  #include <string.h>
  #include <unistd.h>
  
  #include "imsg.h"
  
  int	 imsg_fd_overhead = 0;
  
  static int	 imsg_get_fd(struct imsgbuf *);
  
  void
  imsg_init(struct imsgbuf *ibuf, int fd)
  {
  	msgbuf_init(&ibuf->w);
  	memset(&ibuf->r, 0, sizeof(ibuf->r));
  	ibuf->fd = fd;
  	ibuf->w.fd = fd;
  	ibuf->pid = getpid();
  	TAILQ_INIT(&ibuf->fds);
  }
  
  ssize_t
  imsg_read(struct imsgbuf *ibuf)
  {
  	struct msghdr		 msg;
  	struct cmsghdr		*cmsg;
  	union {
  		struct cmsghdr hdr;
  		char	buf[CMSG_SPACE(sizeof(int) * 1)];
  	} cmsgbuf;
  	struct iovec		 iov;
  	ssize_t			 n = -1;
  	int			 fd;
  	struct imsg_fd		*ifd;
  
  	memset(&msg, 0, sizeof(msg));
  	memset(&cmsgbuf, 0, sizeof(cmsgbuf));
  
  	iov.iov_base = ibuf->r.buf + ibuf->r.wpos;
  	iov.iov_len = sizeof(ibuf->r.buf) - ibuf->r.wpos;
  	msg.msg_iov = &iov;
  	msg.msg_iovlen = 1;
  	msg.msg_control = &cmsgbuf.buf;
  	msg.msg_controllen = sizeof(cmsgbuf.buf);
  
  	if ((ifd = calloc(1, sizeof(struct imsg_fd))) == NULL)
  		return (-1);
  
  again:
  	if (getdtablecount() + imsg_fd_overhead +
  	    (int)((CMSG_SPACE(sizeof(int))-CMSG_SPACE(0))/sizeof(int))
  	    >= getdtablesize()) {
  		errno = EAGAIN;
  		free(ifd);
  		return (-1);
  	}
  
  	if ((n = recvmsg(ibuf->fd, &msg, 0)) == -1) {
  		if (errno == EINTR)
  			goto again;
  		goto fail;
  	}
  
  	ibuf->r.wpos += n;
  
  	for (cmsg = CMSG_FIRSTHDR(&msg); cmsg != NULL;
  	    cmsg = CMSG_NXTHDR(&msg, cmsg)) {
  		if (cmsg->cmsg_level == SOL_SOCKET &&
  		    cmsg->cmsg_type == SCM_RIGHTS) {
  			int i;
  			int j;
  
  			/*
  			 * We only accept one file descriptor.  Due to C
  			 * padding rules, our control buffer might contain
  			 * more than one fd, and we must close them.
  			 */
  			j = ((char *)cmsg + cmsg->cmsg_len -
  			    (char *)CMSG_DATA(cmsg)) / sizeof(int);
  			for (i = 0; i < j; i++) {
  				fd = ((int *)CMSG_DATA(cmsg))[i];
  				if (ifd != NULL) {
  					ifd->fd = fd;
  					TAILQ_INSERT_TAIL(&ibuf->fds, ifd,
  					    entry);
  					ifd = NULL;
  				} else
  					close(fd);
  			}
  		}
  		/* we do not handle other ctl data level */
  	}
  
  fail:
  	free(ifd);
  	return (n);
  }
  
  ssize_t
  imsg_get(struct imsgbuf *ibuf, struct imsg *imsg)
  {
  	size_t			 av, left, datalen;
  
  	av = ibuf->r.wpos;
  
  	if (IMSG_HEADER_SIZE > av)
  		return (0);
  
  	memcpy(&imsg->hdr, ibuf->r.buf, sizeof(imsg->hdr));
  	if (imsg->hdr.len < IMSG_HEADER_SIZE ||
  	    imsg->hdr.len > MAX_IMSGSIZE) {
  		errno = ERANGE;
  		return (-1);
  	}
  	if (imsg->hdr.len > av)
  		return (0);
  	datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
  	ibuf->r.rptr = ibuf->r.buf + IMSG_HEADER_SIZE;
  	if (datalen == 0)
  		imsg->data = NULL;
  	else if ((imsg->data = malloc(datalen)) == NULL)
  		return (-1);
  
  	if (imsg->hdr.flags & IMSGF_HASFD)
  		imsg->fd = imsg_get_fd(ibuf);
  	else
  		imsg->fd = -1;
  
  	memcpy(imsg->data, ibuf->r.rptr, datalen);
  
  	if (imsg->hdr.len < av) {
  		left = av - imsg->hdr.len;
  		memmove(&ibuf->r.buf, ibuf->r.buf + imsg->hdr.len, left);
  		ibuf->r.wpos = left;
  	} else
  		ibuf->r.wpos = 0;
  
  	return (datalen + IMSG_HEADER_SIZE);
  }
  
  int
  imsg_compose(struct imsgbuf *ibuf, uint32_t type, uint32_t peerid, pid_t pid,
      int fd, const void *data, uint16_t datalen)
  {
  	struct ibuf	*wbuf;
  
  	if ((wbuf = imsg_create(ibuf, type, peerid, pid, datalen)) == NULL)
  		return (-1);
  
  	if (imsg_add(wbuf, data, datalen) == -1)
  		return (-1);
  
  	wbuf->fd = fd;
  
  	imsg_close(ibuf, wbuf);
  
  	return (1);
  }
  
  int
  imsg_composev(struct imsgbuf *ibuf, uint32_t type, uint32_t peerid, pid_t pid,
      int fd, const struct iovec *iov, int iovcnt)
  {
  	struct ibuf	*wbuf;
  	int		 i, datalen = 0;
  
  	for (i = 0; i < iovcnt; i++)
  		datalen += iov[i].iov_len;
  
  	if ((wbuf = imsg_create(ibuf, type, peerid, pid, datalen)) == NULL)
  		return (-1);
  
  	for (i = 0; i < iovcnt; i++)
  		if (imsg_add(wbuf, iov[i].iov_base, iov[i].iov_len) == -1)
  			return (-1);
  
  	wbuf->fd = fd;
  
  	imsg_close(ibuf, wbuf);
  
  	return (1);
  }
  
  /* ARGSUSED */
  struct ibuf *
  imsg_create(struct imsgbuf *ibuf, uint32_t type, uint32_t peerid, pid_t pid,
      uint16_t datalen)
  {
  	struct ibuf	*wbuf;
  	struct imsg_hdr	 hdr;
  
  	datalen += IMSG_HEADER_SIZE;
  	if (datalen > MAX_IMSGSIZE) {
  		errno = ERANGE;
  		return (NULL);
  	}
  
  	hdr.type = type;
  	hdr.flags = 0;
  	hdr.peerid = peerid;
  	if ((hdr.pid = pid) == 0)
  		hdr.pid = ibuf->pid;
  	if ((wbuf = ibuf_dynamic(datalen, MAX_IMSGSIZE)) == NULL) {
  		return (NULL);
  	}
  	if (imsg_add(wbuf, &hdr, sizeof(hdr)) == -1)
  		return (NULL);
  
  	return (wbuf);
  }
  
  int
  imsg_add(struct ibuf *msg, const void *data, uint16_t datalen)
  {
  	if (datalen)
  		if (ibuf_add(msg, data, datalen) == -1) {
  			ibuf_free(msg);
  			return (-1);
  		}
  	return (datalen);
  }
  
  void
  imsg_close(struct imsgbuf *ibuf, struct ibuf *msg)
  {
  	struct imsg_hdr	*hdr;
  
  	hdr = (struct imsg_hdr *)msg->buf;
  
  	hdr->flags &= ~IMSGF_HASFD;
  	if (msg->fd != -1)
  		hdr->flags |= IMSGF_HASFD;
  
  	hdr->len = (uint16_t)msg->wpos;
  
  	ibuf_close(&ibuf->w, msg);
  }
  
  void
  imsg_free(struct imsg *imsg)
  {
  	freezero(imsg->data, imsg->hdr.len - IMSG_HEADER_SIZE);
  }
  
  static int
  imsg_get_fd(struct imsgbuf *ibuf)
  {
  	int		 fd;
  	struct imsg_fd	*ifd;
  
  	if ((ifd = TAILQ_FIRST(&ibuf->fds)) == NULL)
  		return (-1);
  
  	fd = ifd->fd;
  	TAILQ_REMOVE(&ibuf->fds, ifd, entry);
  	free(ifd);
  
  	return (fd);
  }
  
  int
  imsg_flush(struct imsgbuf *ibuf)
  {
  	while (ibuf->w.queued)
  		if (msgbuf_write(&ibuf->w) <= 0)
  			return (-1);
  	return (0);
  }
  
  void
  imsg_clear(struct imsgbuf *ibuf)
  {
  	int	fd;
  
  	msgbuf_clear(&ibuf->w);
  	while ((fd = imsg_get_fd(ibuf)) != -1)
  		close(fd);
  }